Airborne fibers and particles are of significance to occupational and environmental health. Many of these pollutants cause respiratory disease including pulmonary fibrosis (asbestos, kaolin, silica, talc), bronchogenic carcinoma (asbestos, hematite) and mesothelioma (asbestos, erionite and other fibers of similar dimension to asbestos). Others are thought to act as carriers for chemical carcinogens in the atmosphere including polycyclic aromatic hydrocarbons in cigarette smoke. A number of particulates or 'nuisance dusts' (cotton, glass) also cause inflammatory changes which can contribute to dermatitis, asthma and chronic respiratory disease. The mechanisms by which mineral dusts cause cell damage and altered proliferation and/or differentiation of cells are unclear. The purpose of this meeting (to be held September 21-23, 1988 in Sherbrooke, Quebec, Canada), the fourth in a series of international workshops occurring approximately every 3-4 years, is to bring together approximately 125 eminent scientists performing "state-of-the-art" clinical and basic research on mechanisms of action of fibers and particulates on 'target' cells of disease. Sessions-in-depth will include: Physico-chemical properties of dusts as related to their pathogenic potential; Molecular biology and oncogenes; Growth factors and mechanisms of proliferation; Mechanisms of inflammation; Involvement of active oxygen species, etc. The presentations and discussion will contribute to our understanding of how particulates cause cell damage, inflammation, and disturbances in growth and will allow the development of preventive and therapeutic approaches to lung disease.